This work represents a small contribution to draw attention towards the effect of the disposal of used lubricating car engine oil into unauthorized places on the environment especially in the present days when a large number of cars are running into the street. These oils contain in addition to its variety of organic compounds a relatively large amount of polluting heavy metals. In chapter one of this thesis, an introduction is given on the pollution and its effects on the environmental air, water and soil. A list of the major pollutants are described and their bad contribution on health of human and after living beings were explained. The second chapter is concern with the experimental part which in could the kinds of oil samples used in this work, the instrument and material employed as well as the analytical methods that have been used to determine some of the components present in oil samples. The results and discussion are presented in chapter three. Arsenic, chromium, lead, magnesium, iron and zinc were the elements analyzed in this work. These element were found in a relatively large concentrations in new oil samples. The concentrations of these elements were found to increase dramatically in the oil samples after using in cares of different brands and models. The relative increase of these metal after usage were as high as 400% compared to the original content of the oil. The concentration of organic compounds that dissolve as results of mixing oil with water were also measured quantitatively by using U.V-visible spectrophotometer. The concentration of these organic compounds in new and used oil at different pH were measured and discussed. This study concluded that the above rnatenals, inorganic as well as orgamc compound, represent a great risk to the environmen, when it is disposed in improper way.